A surprise awaits the nation's highest earners when they file their 2006 tax returns. Their taxes are going down again - whether or not Congress passes the investor tax cuts the lawmakers have been promising. On New Year's Day, two additional tax cuts will kick in, allowing people who earn upward of $200,000 a year to claim bigger write-offs for a spouse, their children and other expenses, like mortgage interest on a vacation home. The bolstered write-offs were enacted in 2001, but with a delayed start date because of their high cost: according to Congressional estimates, the new breaks will cost $27 billion over the short term, exploding to $146 billion from 2010 through 2019. By then, most of the benefits would flow to taxpayers who make more than $1 million a year.